I have visited the Altiplano in Bolivia and the Atacama of Chile. I have been to Chacaltaya.
The Chacaltaya tropical glacier has died. I was there a decade ago and it was obvious that it was a doomed “fossil” glacier, just like the doomed fossil glaciers in the California Sierra that John Muir wrote about a century ago.
There is no mystery here. It is the slow warming (with ups and downs) that has been occurring ever since the end of the last big ice age.
The locals were living off the net melt of old stored (frozen) water, just like other people live by pumping water from ancient aquifers. Unfortunate for them, but not surprising.

I think Gladwell isn’t really pulling his weight in these exchanges; you ever think of trying to take his place? You’re not as well known as an author, but you might have more to say about a bigger variety of topics.